Recently, demands for the development of technology used for analyzing the activity of physiological materials, such as nucleic acids, proteins, enzymes, antibodies, and antigens, have rapidly increased in the world. For such demands, a biochip in which the required physiological material molecules are immobilized on certain tiny regions by adopting semiconductor processing techniques is suggested, so thereby physiologically useful information is easily obtained just by biochemically searching the biochip.
The biochip is in the form of a conventional semiconductor chip, but what is integrated thereon is a bio-organic material such as an enzyme, a protein, an antibody, DNA, a microorganism, animal and/or plant cells and/or organs, a neuron, or the like. The biochip can be classified as a “DNA chip” immobilizing a DNA probe; a “protein chip” immobilizing a protein such as an enzyme, an antibody, an antigen or the like; or a “lab-on-a-chip” which is integrated with pre-treating, biochemical reacting, detecting, and data-analyzing functions to impart an auto-analysis function.
The biochip is a device used for diagnosing infectious diseases and analyzing genes by using an intrinsic function of physiological material and a mimicking function of a living body. It has recently become noteworthy as an essential device of a bio-computer which recognizes and responds to foreign stimulation like a living body and has a superior capacity to currently commercialized semiconductors.
To achieve the successful development of such a biochip, it is important to find a method for immobilizing a physiological material in which an interface between the physiological material and a substrate is efficiently formed, and the inherent functions of the physiological material can be utilized at a maximum level. Generally, the physiological material is immobilized on the surface of a glass plate, a silicon wafer, a microwell plate, a tube, a spherical bead, a surface with a porous layer, etc. by various techniques, for example, by reacting DNA with carbodiimide to activate a 5′-phosphate group of DNA and by reacting the activated DNA with a functional group on the surface of the substrate so as to immobilize the DNA on the substrate.
U.S. Pat. No. 5,858,653 discloses a composition comprising an ion group, such as a quaternary ammonium group, a protonated tertiary amine, or phosphonium, capable of reacting with a target physiological material; and a polymer having a photo-reactive group or a thermochemically reactive group for use in attaching to the surface of a substrate. U.S. Pat. No. 5,981,734 teaches that when DNA is immobilized by a polyacrylamide gel having an amino group or an aldehyde group, the DNA can be bound with a substrate via a stable hybridization bond to easily facilitate carrying out of analysis. U.S. Pat. No. 5,869,272 discloses an attachment layer comprising a chemical selected from dendrimers, star polymers, molecular self-assembling polymers, polymeric siloxanes, and film-forming latexes formed by spin-coating a silicone wafer with aminosilane. U.S. Pat. No. 5,869,272 discloses a method for the determination of a bacteria antigen by detecting a visual color change of an optically active surface. U.S. Pat. No. 5,919,523 discloses a method for preparing a support on which an amino silane-treated substrate is doped with glycine or serine or is coated with an amine, imine, or amide-based organic polymer.
In the above-mentioned patents, the immobilization layer is provided by preparing a self-assembly monolayer of silane molecules. Preferably, the silane is aminoalkoxy silane since it does not produce acidic by-products, and it can provide a molecular layer having a functional group with a relatively high density. Although much research has advanced the obtainment of a uniform monolayer having high-density functional groups using aminoalkoxy silanes, an aminosilane monolayer having a functional group with a uniform and high density and shorter manufacturing time has not been achieved.
U.S. Pat. No. 5,985,551 discloses a method for providing amino groups on a solid substrate by using a photolithography technique on the amino silane treated substrate, the method involving allotting hydrophilic functions on regions to immobilize DNA and fluorosiloxane hydrophobic functions on other regions so as to form a desirable patterned DNA spot on the substrate. This method is advantageous for controlling density of the functional groups by separating immobilizing regions from non-immobilizing regions. However, it has a problem in that the process is very complicated with multiple steps, so it has a longer manufacturing time and is thus inadequate for large-scale production.